JP2022012888A - tire - Google Patents

Abstract

To provide a tire capable of having both tire snow performance and tire noise performance.SOLUTION: In a tire 1, a shoulder land part 31 comprises a plurality of shoulder lug grooves 311 that intersect a tire ground-contact end T and are extended in a tire width direction, and which are terminated within a grounding surface of the shoulder land part 31. In addition, the shoulder lug groove 311 comprises a body part 3111 having a maximum circumferential direction width W1 of the shoulder lug groove 311 and arranged in a central portion of a grounding region of the shoulder land part 31, and an extended part 3112 extended from the body part 3111 and intersecting the tire ground-contact end T. A circumferential direction width W2 of the shoulder lug groove 311 at the tire ground-contact end T has a relation of 0.20≤W2/W1≤0.90 with respect to the maximum circumferential direction width W1.SELECTED DRAWING: Figure 3

Description

The present invention relates to a tire, and more particularly to a tire capable of achieving both snow performance and noise performance of the tire.

In recent all-season tires, there is a problem that the snow performance and noise performance of the tire should be compatible. As a conventional tire relating to such a problem, the technique described in Patent Document 1 is known.

Japanese Unexamined Patent Publication No. 2019-167052

An object of the present invention is to provide a tire having both snow performance and noise performance of the tire.

In order to achieve the above object, the tire according to the present invention is a tire including a peripheral groove extending in the peripheral direction of the tire and a shoulder land portion defined by the peripheral groove, and the shoulder land portion has a shoulder land portion. It is provided with a plurality of shoulder lug grooves that intersect the tire ground contact end and extend in the tire width direction and terminate in the ground contact surface of the shoulder land portion, and the shoulder lug groove is the maximum circumferential width W1 of the shoulder lug groove. A main body portion that is arranged in the center of the ground contact area of the shoulder land portion and an extension portion that extends from the main body portion and intersects the tire ground contact end, and is provided with a shoulder lug groove at the tire ground contact end. The circumferential width W2 is characterized by having a relationship of 0.20 ≦ W2 / W1 ≦ 0.90 with respect to the maximum peripheral width W1.

In the tire according to the present invention, (1) the wide main body portion is arranged in the central portion of the ground contact area of the shoulder land portion, so that the snow column shearing force is secured and the snow traction property of the tire is improved. Further, (2) the narrow extension portion connects the main body portion and the tire ground contact end T, so that the pattern noise of the tire is reduced. Further, (3) the lower limit of the ratio W2 / W1 secures the effect of improving the snow traction property by the extending portion, and the above lower limit ensures the effect of reducing the pattern noise by the extending portion. These have the advantage of achieving both snow performance and noise performance of the tire.

FIG. 1 is a cross-sectional view in the tire meridian direction showing a tire according to an embodiment of the present invention. FIG. 2 is a plan view showing the tread surface of the tire shown in FIG. FIG. 3 is an enlarged view showing the outer shoulder land portion described in FIG. FIG. 4 is an enlarged plan view showing the shoulder lug groove of the outer shoulder land portion described in FIG. FIG. 5 is a cross-sectional view of the shoulder lug groove shown in FIG. 4 in the groove depth direction. FIG. 6 is a cross-sectional view of the shoulder lug groove shown in FIG. 4 in the groove width direction in the groove depth direction. FIG. 7 is an enlarged view showing the inner shoulder land portion described in FIG. FIG. 8 is an enlarged view showing the outer center land portion and the inner center land portion of the tire 1 shown in FIG. FIG. 9 is a chart showing the results of a tire performance test according to an embodiment of the present invention. FIG. 10 is a chart showing the results of a tire performance test according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the drawings. The present invention is not limited to this embodiment. In addition, the components of this embodiment include those that are replaceable and self-explanatory while maintaining the identity of the invention. Further, the plurality of modifications described in this embodiment can be arbitrarily combined within the range of those skilled in the art.

[tire]
FIG. 1 is a cross-sectional view in the tire meridian direction showing a tire according to an embodiment of the present invention. The figure shows a cross-sectional view of a one-sided region in the tire radial direction. Further, the figure shows, as an example, a pneumatic radial tire for a passenger car.

In the figure, the cross section in the tire meridian direction is defined as the cross section when the tire is cut on a plane including the tire rotation axis (not shown). Further, the tire equatorial plane CL is defined as a plane that passes through the midpoint of the measurement point of the tire cross-sectional width defined by JATTA and is perpendicular to the tire rotation axis. Further, the tire width direction is defined as a direction parallel to the tire rotation axis, and the tire radial direction is defined as a direction perpendicular to the tire rotation axis. Further, the point T is a tire ground contact end.

Further, the inside in the vehicle width direction and the outside in the vehicle width direction are defined as the orientation with respect to the vehicle width direction when the tire is mounted on the vehicle. Further, the left and right regions with the tire equatorial plane as a boundary are defined as an outer region in the vehicle width direction and an inner region in the vehicle width direction, respectively. Further, the tire is provided with a mounting direction display unit (not shown) indicating the tire mounting direction with respect to the vehicle. The mounting direction display portion is composed of, for example, marks and irregularities attached to the sidewall portion of the tire. For example, ECE R30 (Article 30 of the European Economic Commission for Europe) requires that a display unit in the vehicle mounting direction be provided on the sidewall portion that is outside in the vehicle width direction when the vehicle is mounted.

The tire 1 has an annular structure centered on a tire rotation axis, and has a pair of bead cores 11 and 11, a pair of bead fillers 12 and 12, a carcass layer 13, a belt layer 14, and a pair of tread rubber 15. The sidewall rubbers 16 and 16 and the pair of rim cushion rubbers 17 and 17 are provided (see FIG. 1).

The pair of bead cores 11 and 11 are formed by winding one or a plurality of bead wires made of steel in an annular shape and multiple times, and are embedded in the bead portion to form the cores of the left and right bead portions. The pair of bead fillers 12 and 12 are arranged on the outer periphery of the pair of bead cores 11 and 11 in the tire radial direction to reinforce the bead portion.

The carcass layer 13 has a single-layer structure composed of one carcass ply or a multi-layer structure formed by laminating a plurality of carcass plies, and is bridged between the left and right bead cores 11 and 11 in a toroidal shape to form a tire skeleton. To configure. Further, both ends of the carcass layer 13 are wound and locked outward in the tire width direction so as to wrap the bead core 11 and the bead filler 12. Further, the carcass ply of the carcass layer 13 is formed by coating a plurality of carcass cords made of steel or an organic fiber material (for example, aramid, nylon, polyester, rayon, etc.) with coated rubber and rolling them. It has a cord angle of 100 [deg] or less (defined as an inclination angle in the longitudinal direction of the carcass cord with respect to the tire circumferential direction).

The belt layer 14 is formed by laminating a plurality of belt plies 141 to 143, and is arranged so as to be hung around the outer periphery of the carcass layer 13. The belt plies 141 to 143 include a pair of cross belts 141 and 142 and a belt cover 143.

The pair of crossed belts 141 and 142 are formed by coating a plurality of belt cords made of steel or organic fiber with coated rubber and rolling them, and have an absolute value of 15 [deg] or more and 55 [deg] or less. Have. Further, the pair of crossing belts 141 and 142 have code angles having different signs from each other (defined as an inclination angle in the longitudinal direction of the belt cord with respect to the tire circumferential direction), and the longitudinal directions of the belt cords intersect each other. (So-called cross-ply structure). Further, the pair of cross belts 141 and 142 are laminated and arranged on the outer side of the carcass layer 13 in the tire radial direction.

The belt cover 143 is configured by covering a belt cover cord made of steel or an organic fiber material with a coated rubber, and has a cord angle of 0 [deg] or more and 10 [deg] or less in absolute value. Further, the belt cover 143 is, for example, a strip material formed by coating one or a plurality of belt cover cords with a coated rubber, and a plurality of the strip materials are used in the tire circumferential direction with respect to the outer peripheral surfaces of the cross belts 141 and 142. It is constructed by winding it in a spiral shape. Further, the belt cover 143 is arranged so as to cover the entire area of the cross belts 141 and 142.

The tread rubber 15 is arranged on the outer periphery of the carcass layer 13 and the belt layer 14 in the tire radial direction to form a tread portion of the tire 1. The pair of sidewall rubbers 16 and 16 are arranged on the outer sides of the carcass layer 13 in the tire width direction, respectively, to form the left and right sidewall portions. The pair of rim cushion rubbers 17 and 17 extend from the inside in the tire radial direction to the outside in the tire width direction of the rewinding portion of the left and right bead cores 11 and 11 and the carcass layer 13 to form a rim fitting surface of the bead portion.

[Tread surface]
FIG. 2 is a plan view showing the tread surface of the tire shown in FIG. The figure shows the tread surface of an all-season tire. In the figure, the tire circumferential direction means the direction around the tire rotation axis. Further, the reference numeral T is a tire contact end, and the dimension symbol TW is a tire contact width. Further, in the figure, since the tire 1 has a tread surface that is substantially point-symmetrical, a part of the reference numerals of the components in the region on the right side of the figure is omitted.

As shown in FIG. 2, the tire 1 has three or more (three in FIG. 2) peripheral grooves 21 to 23 and four or more rows (four rows in FIG. 2) divided into these peripheral grooves 21 to 23. The land portion 31 to 34 of the above is provided on the tread surface.

The peripheral grooves 21 to 23 are grooves extending in the tire peripheral direction, and have a continuous annular structure over the entire circumference of the tire. Further, in the configuration of FIG. 2, the tire 1 is provided with three peripheral grooves 21 to 23, and each of these peripheral grooves 21 to 23 is a main groove having an obligation to display a wear indicator specified in JATTA. It has a maximum groove width of 4.0 [mm] or more and a maximum groove depth of 6.5 [mm] or more.

The groove width is measured as the distance between the opposing groove walls at the groove opening in a no-load state in which the tire is mounted on the specified rim and filled with the specified internal pressure. In a configuration having a notch or a chamfered portion in the groove opening, the groove width is measured at the intersection of the extension line of the tread tread and the extension line of the groove wall in a cross-sectional view parallel to the groove width direction and the groove depth direction. Is measured.

The groove depth is measured as the distance from the tread tread to the bottom of the groove in a no-load state in which the tire is mounted on the specified rim and the specified internal pressure is applied. Further, in a configuration having a partially uneven portion or a sipe at the groove bottom, the groove depth is measured by excluding these.

The specified rim means the "standard rim" specified in JATMA, the "Design Rim" specified in TRA, or the "Measuring Rim" specified in ETRTO. The specified internal pressure means the "maximum air pressure" specified in JATTA, the maximum value of "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified in TRA, or "INFLATION PRESSURES" specified in ETRTO. The specified load means the "maximum load capacity" specified in JATTA, the maximum value of "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified in TRA, or the "LOAD CAPACITY" specified in ETRTO. However, in JATTA, in the case of a passenger car tire, the specified internal pressure is an air pressure of 180 [kPa], and the specified load is 88 [%] of the maximum load capacity at the specified internal pressure.

Further, in FIG. 2, among the plurality of peripheral grooves 21 to 23, the outermost peripheral grooves 21 and 23 in the tire width direction are defined as shoulder peripheral grooves, and the other peripheral grooves 22 are defined as center peripheral grooves. Further, the shoulder peripheral groove 21 on the outer side in the vehicle width direction is defined as the outer shoulder peripheral groove, and the shoulder peripheral groove 23 on the inner side in the vehicle width direction is defined as the inner shoulder peripheral groove.

For example, in the configuration of FIG. 2, the maximum groove width Wg1 (dimension symbol omitted in the figure) of the outer shoulder peripheral groove 21 is narrower than the maximum groove width Wg3 (dimension symbol omitted in the figure) of the inner shoulder peripheral groove 23. Specifically, the maximum groove width Wg1 of the outer shoulder peripheral groove 21 has a relationship of 0.25 ≦ Wg1 / Wg3 ≦ 0.60 with respect to the maximum groove width Wg3 of the inner shoulder peripheral groove 23. As a result, the rigidity of the contact area outside the vehicle width direction with the tire equatorial CL as the boundary is increased to improve the dry performance of the tire, and the groove area of the contact area inside the vehicle width direction is increased to increase the tire. Wet performance is improved.

Further, in the configuration of FIG. 2, the left and right regions with the tire equatorial plane CL as a boundary have shoulder peripheral grooves 21 and 23, respectively, and a single center peripheral groove 22 is arranged on the tire equatorial plane CL. There is. The four rows of land portions 31 to 34 are partitioned by these peripheral grooves 21 to 23. However, the present invention is not limited to this, and four or more peripheral grooves may be arranged, or one peripheral groove may be arranged at a position off the tire equatorial plane CL (not shown).

The land portions 31 to 34 are divided into peripheral grooves 21 to 23, and have an annular tread extending over the entire circumference of the tire.

Further, in FIG. 2, among a plurality of land portions 31 to 34, the land portions 31 and 34 on the outer side in the tire width direction divided into the shoulder peripheral grooves 21 and 23 are defined as the shoulder land portions, and the land on the inner side in the tire width direction is defined. Units 32 and 33 are defined as the center land area. Further, among the pair of shoulder land portions 31, 34, the shoulder land portion 31 on the outer side in the vehicle width direction is defined as the outer shoulder land portion, and the shoulder land portion 34 on the inner side in the vehicle width direction is defined as the inner shoulder land portion. .. Further, of the pair of adjacent center land portions 32, 33, the center land portion 32 located outside in the vehicle width direction is defined as the outer center land portion, and the center land portion 33 inside in the vehicle width direction is defined as the inner center land portion. Define.

In the configuration including the three peripheral grooves 21 to 23 as shown in FIG. 2, a pair of shoulder land portions 31 and 34 and a pair of center land portions 32 and 33 are defined. Further, for example, in a configuration including four or more peripheral grooves, a pair of shoulder land portions and three or more rows of center land portions are defined (not shown).

Further, in FIG. 2, the maximum contact widths Wb2 and Wb3 of the outer center land portion 32 and the inner center land portion 33 are 0.20 ≦ Wb2 / TW ≦ 0.30_ and 0.15 ≦ Wb3 with respect to the tire contact width TW. It has a relationship of / TW ≦ 0.25. Further, in the configuration of FIG. 2, the maximum ground contact width Wb2 of the outer center land portion 32 is wider than the maximum ground contact width Wb3 of the inner center land portion 33, specifically 1.20 ≦ Wb2 / Wb3 ≦ 1.40. Have a relationship.

The ground contact widths Wb2 and Wb3 of the land portion are the same as those of the land portion when the tire is mounted on the specified rim to apply the specified internal pressure and the tire is placed perpendicular to the flat plate in a stationary state to apply a load corresponding to the specified load. It is measured as a linear distance in the tire axial direction on the contact surface with the flat plate.

The tire contact width TW is the contact surface between the tire and the flat plate when the tire is mounted on the specified rim to apply the specified internal pressure and the tire is placed perpendicular to the flat plate in a stationary state and a load corresponding to the specified load is applied. It is measured as a linear distance in the tire axial direction in.

[Outer shoulder land]
FIG. 3 is an enlarged view showing the outer shoulder land portion 31 described in FIG. The figure shows a plan view from the outer shoulder peripheral groove 21 to the tread end. FIG. 4 is an enlarged plan view showing the shoulder lug groove 311 of the outer shoulder land portion 31 described in FIG. 5 and 6 are a cross-sectional view (FIG. 5) in the groove depth direction and a cross-sectional view (FIG. 6) in the groove width direction of the shoulder lug groove 311 shown in FIG. In these figures, FIG. 5 shows a cross-sectional view of the shoulder lug groove 311 along the longitudinal direction, and FIG. 6 shows a cross-sectional view at the maximum circumferential width position.

In the configuration of FIG. 2, as shown in FIG. 3, the outer shoulder land portion 31 includes a plurality of shoulder lug grooves 311 (311A to 311D).

The outer shoulder lug groove 311 has a so-called semi-closed structure, intersects the tire ground contact end T, extends in the tire width direction, and terminates in the ground contact surface of the outer shoulder land portion 31. Further, a plurality of outer shoulder lug grooves 311 are arranged in the tire circumferential direction with a predetermined pitch length P11. For example, in the configuration of FIG. 3, the outer shoulder lug groove 311 is not connected to another groove or sipe in the ground plane of the outer shoulder land portion 31 and is surrounded by a continuous ground plane of the outer shoulder land portion 31. It has been.

Further, in FIG. 4, the maximum circumferential width W1 of the outer shoulder lug groove 311 has a relationship of 0.10 ≦ W1 / P11 ≦ 0.50 with respect to the pitch length P11 (see FIG. 3) of the outer shoulder lug groove 311. It has a relationship of 0.20 ≦ W1 / P11 ≦ 0.30. Further, the circumferential width W2 of the outer shoulder lug groove 311 at the tire ground contact end T has a relationship of 0.20 ≦ W2 / W1 ≦ 0.90 with respect to the maximum circumferential width W1 of the outer shoulder lug groove 311. It preferably has a relationship of 0.30 ≦ W2 / W1 ≦ 0.50.

The circumferential widths W1 and W2 of the outer shoulder lug groove 311 are measured as the distance in the tire circumferential direction between the opposing groove walls at the groove opening in a no-load state in which the tire is mounted on the specified rim and the specified internal pressure is filled. Will be done. In the configuration in which the notch or chamfer is provided in the groove opening, the intersection of the extension line of the tread tread and the extension line of the groove wall in the cross-sectional view parallel to the groove width direction and the groove depth direction is used as a measurement point in the circumferential direction. The width is measured.

In the above configuration, (1) the wide main body portion 3111 is arranged in the central portion of the ground contact region of the shoulder land portion 31, so that the snow column shearing force is secured and the snow traction property of the tire is improved. Further, (2) since the narrow extension portion 3112 connects the main body portion 3111 and the tire contact end T, the tire is compared with the configuration in which the wide main body portion extends to the tire contact end (not shown). Pattern noise is reduced. Further, (3) the lower limit of the ratio W2 / W1 secures the effect of improving the snow traction property by the extending portion 3112, and the above lower limit ensures the effect of reducing the pattern noise by the extending portion 3112. As a result, both the snow performance and the noise performance of the tire are compatible.

Further, in FIG. 4, the distance D1 in the tire width direction from the tire ground contact end T to the maximum circumferential width position of the outer shoulder lug groove 311 (defined as a position where the circumferential width is the maximum circumferential width W1) is , 0.50 ≦ D1 / Wb1 ≦ 0.90 with respect to the maximum contact width Wb1 of the outer shoulder land portion 311, preferably 0.60 ≦ D1 / Wb1 ≦ 0.70.

In the configuration of FIG. 4, the outer shoulder lug groove 311 has a one-sided widening shape in which the width in the circumferential direction is widened in one direction in the tire circumferential direction (lower part in the figure in FIG. 4) from the tire contact end T toward the inside in the tire width direction. Have. Further, the circumferential width of the outer shoulder lug groove 311 monotonically increases from the tire ground contact end T toward the maximum circumferential width position of the outer shoulder lug groove 311. Further, the maximum circumferential width position of the outer shoulder lug groove 311 is located in the outer shoulder peripheral groove 21 with respect to the center line (not shown) in the tire width direction of the outer shoulder land portion 311.

Further, as shown in FIG. 4, the outer shoulder lug groove 311 includes a main body portion 3111 and an extension portion 3112.

The main body portion 3111 is a groove portion having the maximum circumferential width W1 of the outer shoulder lug groove 311 described above, and constitutes an end portion inside the outer shoulder lug groove 311 in the tire width direction. Further, the main body portion 3111 is arranged in the central portion of the ground contact region of the outer shoulder land portion 31. Specifically, the distance D2 from the tire ground contact end T to the innermost point P1 in the tire width direction of the outer shoulder lug groove 311 is 0.55 ≦ D2 / Wb1 with respect to the maximum ground contact width Wb1 of the outer shoulder land portion 31. It has a relationship of ≦ 0.95, preferably 0.75 ≦ D2 / Wb1 ≦ 0.85.

The extending portion 3112 is a groove portion connecting the main body portion 3111 and the tire ground contact end T, and extends from the main body portion 3111 in the tire width direction and intersects the tire ground contact end T. Further, the extending portion 3112 has a substantially constant circumferential width, and specifically, a continuous circumferential width of 1.00 times or more and 1.20 times or less with respect to the circumferential width W2 at the tire ground contact end T. Has a width. Therefore, the boundary between the extending portion 3112 and the main body portion 3111 is defined as a position having a circumferential width W2'that is 1.20 times the circumferential width W2. Therefore, the circumferential width of the outer shoulder lug groove 311 expands stepwise from the inner end portion of the extending portion 3112 in the tire width direction toward the main body portion 3111.

Further, in FIG. 4, it is preferable that the entire extending portion 3112 has a groove width of 2.0 [mm] or more and a groove depth of 2.0 [mm] or more (dimension symbols omitted in the figure). As a result, the extension portion 3112 opens when the tire touches the ground, and the effect of improving the snow traction property of the extension portion 3112 is ensured.

Further, in FIG. 4, the distance D3 from the tire ground contact end T to the inner end portion of the extension portion 3112 in the tire width direction is 0.10 ≦ D3 / Wb1 ≦ with respect to the maximum ground contact width Wb1 of the outer shoulder land portion 31. It has a relationship of 0.40, preferably 0.25 ≦ D3 / Wb1 ≦ 0.35. For example, in the configuration of FIG. 4, the circumferential width of the extending portion 3112 increases monotonically from the tire ground contact end T toward the inside in the tire width direction, and the circumference at the tire ground contact end T at the boundary with the main body portion 3111. It has a circumferential width W2'that is 1.10 times the direction width W2.

Further, in the configuration of FIG. 4, as described above, the outer shoulder lug groove 311 has a step shape (or knife) in which the width in the circumferential direction is widened in one direction in the tire circumferential direction from the tire ground contact end T toward the inside in the tire width direction. Shape). Further, the main body portion 3111 described above constitutes a widening portion of the step shape, and the extending portion 3112 constitutes a narrowing portion. Further, the edge portion E1 (hereinafter referred to as the first edge portion) of the outer shoulder lug groove 311 on the non-widening side (or the back side of the knife shape) of the step shape has a linear shape or a gentle arc shape. , It extends from the tire ground contact end T to the maximum circumferential width position of the outer shoulder lug groove 311. Further, the edge portion E2 (hereinafter referred to as the second edge portion) of the outer shoulder lug groove 311 on the widening side (or the blade side of the knife shape) of the step shape has a linear shape or a gentle arc shape, and is the first. It is arranged so as to face one edge portion E1 and partitions the main body portion 3111. Further, the second edge portion E2 extends from the innermost point P1 in the tire width direction of the outer shoulder lug groove 311 toward the tire contact end T side.

Further, in FIG. 4, the inclination angle θb of the second edge portion E2 with respect to the tire circumferential direction at the maximum circumferential width position is 5 [deg] ≦ θa − with respect to the inclination angle θa of the first edge portion E1 with respect to the tire circumferential direction. It has a relationship of θb ≦ 30 [deg], and preferably has a relationship of 5 [deg] ≦ θa−θb ≦ 15 [deg]. Further, the inclination angle θa of the first edge portion is in the range of 50 [deg] ≦ θa ≦ 90 [deg], preferably in the range of 70 [deg] ≦ θa ≦ 90 [deg].

Further, as shown in FIG. 4, the circumferential width of the main body portion 3111 faces the maximum circumferential width position of the outer shoulder lug groove 311 in the region Rm between the first edge portion E1 and the second edge portion E2. Widening. At this time, a point P2 on the second edge portion E2 in which the circumferential width in the region Rm is 0.80 times the circumferential width W1'with respect to the maximum circumferential width W1 is defined. At this time, the distance D4 from the point P2 to the maximum circumferential width position of the outer shoulder lug groove 311 has a relationship of 0.20 ≦ D4 / Wb1 ≦ 0.80 with respect to the maximum contact width Wb1 of the outer shoulder land portion 31. It has a relationship of 0.20 ≦ D4 / Wb1 ≦ 0.30.

The inclination angles θa and θb are measured as angles on the acute angle side formed by the tangents of the edge portions E1 and E2 at the maximum circumferential width position with respect to the tire circumferential direction.

Further, in the configuration of FIG. 4, the outer shoulder lug groove 311 has a V-shaped end portion having the innermost point P1 in the tire width direction as an apex. Further, the bending angle φ of the V-shape is in the range of 30 [deg] ≦ φ ≦ 80 [deg], preferably in the range of 50 [deg] ≦ φ ≦ 60 [deg].

The bending angle φ of the V-shape is measured as the angle formed by the tangents of the left and right sides E2 and Ee of the V-shape at the innermost point P1.

Further, in the configuration of FIG. 4, the second edge portion E2 for partitioning the main body portion 3111 passes through a linear edge portion (reference numeral omitted in the figure) with respect to the third edge portion E3 for partitioning the extension portion 3112. Is connected. However, the present invention is not limited to this, and the second edge portion E2 and the third edge portion E3 may be connected via an arc-shaped or S-shaped edge portion (not shown).

Further, in FIG. 5, the relationship between the maximum groove depth H11 of the outer shoulder lug groove 311 in the tire ground contact region and the maximum groove depth Hg1 of the outer shoulder peripheral groove 21 is 0.50 ≦ H11 / Hg1 ≦ 0.90. , And preferably has a relationship of 0.70 ≦ H11 / Hg1 ≦ 0.80. In the configuration of FIG. 4, the outer shoulder lug groove 311 has a maximum groove depth H11 at the maximum circumferential width position. Further, in FIG. 6, the left and right groove wall angles α (α1, α2) of the outer shoulder lug groove 311 at the maximum circumferential width position are in the range of 1 [deg] ≤ α ≤ 20 [deg], preferably 4. It is in the range of [deg] ≤ α ≤ 15 [deg].

The groove wall angles α1 and α2 are measured as angles formed by the groove wall and the tread surface of the outer shoulder land portion 31.

Further, in the configuration of FIG. 2, as shown in FIG. 3, the outer shoulder land portion 31 includes a plurality of sipes 312.

The sipe 312 is a notch formed in the land portion, and has a sipe width of less than 1.0 [mm] and a sipe depth of 5.0 [mm] or more, so that the sipe 312 is closed when the tire touches the ground. Further, the sipe 312 crosses the outer shoulder land portion 31 in the tire width direction and opens to both the outer shoulder peripheral groove 21 and the tire ground contact end T. Further, by arranging a single sipe 312 between adjacent outer shoulder lug grooves 311 and 311, the sipe 312 and the outer shoulder lug groove 311 are alternately arranged in the tire circumferential direction. Further, it is preferable that the sipe 312 is a three-dimensional sipe having a three-dimensional groove wall surface. As a result, the rigidity of the land portion when the tire touches the ground is increased, and the snow traction property of the tire is improved.

Further, in the configuration of FIG. 2, as shown in FIG. 3, the outer shoulder land portion 31 includes an auxiliary groove 313 (313A, 313B).

The auxiliary groove 313 is arranged in the tire non-grounded region (so-called buttress portion), and is connected to the terminal portion of the outer shoulder lug groove 311 in the tire non-grounded region and extends in the tire circumferential direction. In the configuration of FIG. 3, the outer shoulder land portion 31 includes first and second auxiliary grooves 313A and 313B, and these auxiliary grooves 313A and 313B are alternately arranged in the tire circumferential direction. Further, the first and second auxiliary grooves 313A and 313B have a linear shape or a gentle arc shape. Further, the inclination angles δ (δa, δb) of the first and second auxiliary grooves 313A and 313B with respect to the tire circumferential direction are 0 [deg] ≤ δa ≤ 10 [deg], 0 [deg] ≤ δb ≤ 15 [deg]. It is preferably in the range of 3 [deg] ≤ δa ≤ 7 [deg], 5 [deg] ≤ δb ≤ 10 [deg]. Further, the first and second auxiliary grooves 313A and 313B are inclined in opposite directions with respect to the tire circumferential direction.

The inclination angles δa and δb of the auxiliary grooves 313A and 313B are measured as the inclination angles of the virtual straight line connecting both ends of the auxiliary grooves 313A and 313B in the longitudinal direction in the tread development view with respect to the tire circumferential direction.

Further, as shown in FIG. 3, the first auxiliary groove 313A is connected to the end portions of the three adjacent outer shoulder lug grooves 311A to 311C and extends in the tire circumferential direction. Specifically, the first auxiliary groove 313A is connected to the end of the first outer shoulder lug groove 311A in an L shape at one end and extends in the tire circumferential direction, and the other end. Terminate in the tire non-grounded area without connecting to other grooves, sipes or tread ends. Further, the second and third outer shoulder lug grooves 311B and 311C are connected to the first auxiliary groove 313A from the side. As a result, the end portions of the first to third outer shoulder lug grooves 311A to 311C are connected in an E shape. Further, the distance La between the end portion of the first auxiliary groove 313A and another groove (first outer shoulder lug groove 311A in FIG. 3) is 0.05 ≦ La / with respect to the pitch length P11 of the outer shoulder lug groove 311. It has a relationship of P11 ≦ 0.20, preferably 0.05 ≦ La / P11 ≦ 0.10. Further, it is preferable that the distance La is in the range of 1.0 [mm] ≦ La.

On the other hand, the second auxiliary groove 313B is connected to the end portion of the single outer shoulder lug groove 311D and extends in the tire circumferential direction. Specifically, the second auxiliary groove 313B is connected to the end of the fourth outer shoulder lug groove 311D in an L shape at one end and extends in the tire circumferential direction, and the other end. Terminate in the tire non-grounded area without connecting to other grooves, sipes or tread ends. Further, the second auxiliary groove 313B extends in the same direction as the tire circumferential direction with respect to the first auxiliary groove 313A. Further, the overlap amount Lb between the first auxiliary groove 313A and the second auxiliary groove 313B in the tire circumferential direction has a relationship of 0.30 ≦ Lb / P11 ≦ 0.80 with respect to the pitch length P11 of the outer shoulder lug groove 311. , And preferably has a relationship of 0.60 ≦ Lb / P11 ≦ 0.70. Further, it is preferable that the overlap amount Lb is in the range of 10 [mm] ≦ La.

[Inner shoulder land]
FIG. 7 is an enlarged view showing the inner shoulder land portion 34 described in FIG.

In the configuration of FIG. 2, as shown in FIG. 7, the inner shoulder land portion 34 includes a plurality of inner shoulder lug grooves 341 and a plurality of sipes 342.

The inner shoulder lug groove 341 has a so-called semi-closed structure, intersects the tire ground contact end T, extends in the tire width direction, and terminates in the ground contact surface of the inner shoulder land portion 34. Further, a plurality of inner shoulder lug grooves 341 are arranged in the tire circumferential direction with a predetermined pitch length. In the configuration of FIG. 2, the inner shoulder lug groove 341 has the same structure as the outer shoulder lug groove 311 and is arranged point-symmetrically with respect to the outer shoulder lug groove 311. Therefore, the description of the inner shoulder lug groove 341 will be omitted here.

The sipe 342 crosses the inner shoulder land portion 34 in the tire width direction and opens to both the inner shoulder peripheral groove 23 and the tire ground contact end T. Further, by arranging a single sipe 342 between the adjacent inner shoulder lug grooves 341 and 341, the sipe 342 and the inner shoulder lug groove 341 are alternately arranged in the tire circumferential direction. Further, in the configuration of FIG. 2, as shown in FIG. 3, the sipe 342 extends to the tread end.

In the configuration of FIG. 2, the inner shoulder land portion 34 does not include the auxiliary groove 313 arranged in the outer shoulder land portion 31. Therefore, the end portion of the inner shoulder lug groove 341 in the tire non-grounded region is terminated without being connected to other grooves.

[Outer center land and inner center land]
In the configuration of FIG. 2, the outer center land portion 32 includes a plurality of outer main lug grooves 321 and a plurality of outer center blocks 322.

The outer main lug groove 321 penetrates the outer center land portion 32 in the tire width direction and opens to the left and right edge portions of the outer center land portion 32. Further, the outer main lug groove 321 is inclined with respect to the tire width direction. Further, the outer main lug groove 321 has a maximum groove width of 4.0 [mm] or more and a maximum groove depth of 6.5 [mm] or more (not shown). Further, a plurality of outer main lug grooves 321 are arranged in the tire circumferential direction with a predetermined pitch length P21.

The outer center block 322 is divided into adjacent outer main lug grooves 321 and 321. Further, a plurality of outer center blocks 322 are arranged in a row in the tire circumferential direction. Further, as described above, the outer main lug groove 321 is inclined with respect to the tire width direction, so that the outer center block 322 has a tread surface having a substantially parallel quadrilateral shape.

Further, as shown in FIG. 2, the inner center land portion 33 includes a plurality of inner main lug grooves 331 and a plurality of inner center blocks 332.

The inner main lug groove 331 penetrates the inner center land portion 33 in the tire width direction and opens to the left and right edge portions of the inner center land portion 33. Further, the inner main lug groove 331 is inclined with respect to the tire width direction. Further, a plurality of inner main lug grooves 331 are arranged in the tire circumferential direction with a predetermined pitch length (dimension symbols omitted in the drawing).

Further, as shown in FIG. 2, the inner main lug groove 331 extends along the extension line of the groove center line of the outer main lug groove 321. Specifically, the outer main lug groove 321 and the inner main lug groove 331 extend along a single straight line or arc. Therefore, the pair of outer main lug grooves 321 and the inner main lug groove 331 form a long through lug groove that penetrates the outer center land portion 32 and the inner center land portion 33 in the tire width direction. Further, a plurality of through lug grooves (321, 331) are arranged in the tire circumferential direction with a predetermined pitch length P21. Further, the inclination angle θ1 of the through lug groove (321, 331) with respect to the tire circumferential direction is in the range of 55 [deg] ≤ θ1 ≤ 85 [deg], and is preferably 65 [deg] ≤ θ1 ≤ 75 [deg]. Is in the range of. This enhances traction and steering stability on snowy roads.

The inclination angle θ1 of the through lug groove (321, 331) is measured as an angle formed by a virtual straight line connecting the left and right openings of the through lug groove (321, 331) and the tire circumferential direction.

Further, the inner main lug groove 331 has a maximum groove width of 3.0 [mm] or more and a maximum groove depth of 4.5 [mm] or more (dimension symbols omitted in the figure). Further, as shown in FIG. 2, it is preferable that the maximum groove width of the inner main lug groove 331 of the inner center land portion 33 is larger than the maximum groove width of the outer main lug groove 321 of the outer center land portion 32. In such a configuration, the maximum groove width of the outer main lug groove 321 on the outer side in the vehicle width direction is narrow, so that the passing noise performance of the tire is improved. On the other hand, since the maximum groove width of the inner main lug groove 331 on the inner side in the vehicle width direction is large, the snow traction performance of the tire is properly ensured. As a result, both the snow performance and the noise performance of the tire are compatible. Further, as shown in FIG. 2, it is preferable that the groove width of the long through lug groove including the outer main lug groove 321 and the inner main lug groove 331 gradually decreases from the inner side in the tire width direction to the outer side. This effectively enhances the noise performance of the tire.

The inner center block 332 is divided into adjacent inner main lug grooves 331 and 331. Further, a plurality of inner center blocks 332 are arranged in a row in the tire circumferential direction. Further, as described above, the inner main lug groove 331 is inclined with respect to the tire width direction, so that the inner center block 332 has a tread surface having a substantially parallel quadrilateral shape.

[Center block groove unit]
FIG. 8 is an enlarged view showing the outer center land portion 32 and the inner center land portion 33 of the tire 1 shown in FIG. The figure shows a pair of adjacent outer center blocks 322 and an inner center block 332.

In the configuration of FIG. 2, as described above, the outer main lug groove 321 of the outer center land portion 32 and the inner main lug groove 331 of the inner center land portion 33 form the outer center land portion 32 and the inner center land portion 33 in the tire width direction. It constitutes a long through lug groove that penetrates through the tire. Further, a plurality of through lug grooves (321, 331) are arranged in the tire circumferential direction with a predetermined pitch length P21. Therefore, the outer center block 322 of the outer center land portion 32 and the inner center block 332 of the inner center land portion 33 are arranged so that the edge portions in the tire circumferential direction are aligned, and a plurality of sets of outer center blocks 322 and the inner center are arranged. The blocks 332 are arranged in the tire circumferential direction with a predetermined pitch length P21.

Further, in the configuration of FIG. 2, as shown in FIG. 8, a pair of adjacent outer center blocks 322 and an inner center block 332 include a groove unit 3. The groove unit 3 forms a characteristic tread pattern in the center region of the tread portion. Hereinafter, the groove unit 3 will be described in detail.

In FIG. 2, the groove unit 3 is composed of an L-shaped lug groove 323 of the outer center land portion 32 and an I-shaped lug groove 333 of the inner center land portion 33, which will be described later, and has an L-shaped lug groove 323 as a blade as a whole. It has a sickle-shaped shape with a handle of the character lug groove 333.

In the configuration of FIG. 2, the outer center land portion 32 includes a plurality of L-shaped lug grooves 323 in addition to the outer main lug groove 321 and the outer center block 322 described above.

As shown in FIG. 2, the L-shaped lug groove 323 has an L-shaped or V-shaped bent shape in a tread plan view. Further, the L-shaped lug groove 323 is terminated in the outer center land portion 32 at one end (hereinafter, simply referred to as “termination”), and the other end (hereinafter, simply referred to as “opening”). .) Opens at the edge of the outer center land portion 32 on the CL side of the tire equatorial plane. Further, the L-shaped lug groove 323 has a maximum groove width of 4.0 [mm] or more and a maximum groove depth of 4.5 [mm] or more. Further, the plurality of L-shaped lug grooves 323 are arranged in the tire circumferential direction with the above-mentioned L-shaped or V-shaped directions aligned. Further, each of the outer center blocks 322 includes a single L-shaped lug groove 323. Therefore, the number of pitches of the L-shaped lug groove 323 is equal to the number of pitches of the outer main lug groove 321 and the outer center block 322.

Further, as shown in FIG. 8, the opening of the L-shaped lug groove 323 is arranged in the middle of the pair of outer main lug grooves 321 (through lug grooves 321 and 331) adjacent to each other in the tire circumferential direction. Specifically, the distance (not shown) between the opening of the L-shaped lug groove 323 and the opening of the outer main lug groove 321 in the tire circumferential direction is 30 [%] with respect to the pitch length P21 of the outer main lug groove 321. ] Or more and 70 [%] or more, preferably 35 [%] or more and 65 [%] or less.

Further, as shown in FIG. 8, a virtual straight line (not shown) passing through the opening and the end of the L-shaped lug groove 323 is inclined in the direction opposite to the inclination direction of the outer main lug groove 321 in the tire circumferential direction. ing.

Further, as shown in FIG. 8, the opening portion, the terminal portion, and the L-shaped top portion of the L-shaped lug groove 323 are arranged so as to be offset from each other in the tire circumferential direction. Further, the opening of the L-shaped lug groove 323 is located between the end portion and the top portion of the L-shaped lug groove 323 in the tire circumferential direction. Therefore, the L-shaped lug groove 323 extends from the opening toward the top in one direction in the tire circumferential direction (lower part in the figure), and then extends from the top toward the end in the other direction in the tire circumferential direction (FIG. It has an L-shape extending in the middle and upper part).

Further, as shown in FIG. 8, the portion from the opening of the L-shaped lug groove 323 to the top of the L-shape (that is, the bending point of the groove center line) and the portion from the top to the end are in the tire circumferential direction. On the other hand, they tilt in opposite directions. Therefore, the top of the L-shaped lug groove 323 projects in one direction in the tire circumferential direction. In the configuration of FIG. 8, as shown in FIG. 2, the portion from the opening to the top of the L-shaped lug groove 323 is inclined toward the upper part of the drawing toward the tire equatorial plane CL side, and the portion from the top to the end is shown in the drawing. It is inclined upward toward the tire contact end T side. Further, the top of the L-shaped lug groove 323 projects downward in the drawing.

In the above configuration, since the outer center land portion 32 in the tread portion center region includes the L-shaped lug groove 323 bent in an L shape, the outer center land portion 32 is linear instead of the L-shaped lug groove 323 described above. Alternatively, as compared with the configuration provided with the arcuate semi-closed lug groove, the extending length of the lug groove on the tread surface of the outer center land portion 32 is increased, and the snow performance of the tire is improved. Further, as compared with the configuration in which the outer center land portion is provided with a through lug groove instead of the L-shaped lug groove (not shown), the air column resonance sound is reduced and the noise outside the vehicle is reduced. This makes it possible to improve the noise performance of the tire while ensuring the snow performance of the tire.

Further, in the above configuration, since the portion from the opening to the top and the portion from the top to the end of the L-shaped lug groove 323 are inclined in opposite directions with respect to the tire circumferential direction, the L-shaped lug groove 323 Compared with the configuration in which the above-mentioned portions are inclined in the same direction with respect to the tire circumferential direction (not shown), the snow turning performance of the tire is improved. Further, since the L-shaped lug groove 323 has a shape that is convex in one direction in the tire circumferential direction (lower part of the drawing in FIG. 8), the top of the L-shaped lug groove is convex in the tire width direction (not shown). In comparison, the snow traction performance of the tire is improved.

Further, in FIG. 8, the inclination angle of the portion from the opening to the top of the L-shaped lug groove 323 with respect to the tire circumferential direction (dimension symbol omitted in the figure) is in the range of 20 [deg] or more and 90 [deg] or less. , Preferably in the range of 40 [deg] or more and 70 [deg] or less. Further, the extending distance of the portion from the opening to the top of the L-shaped lug groove 323 in the tire width direction (dimension symbol omitted in the figure) is 10 [%] with respect to the maximum contact width Wb2 of the outer center land portion 32. It is in the range of 50 [%] or more, preferably 20 [%] or more and 40 [%] or less.

The inclination angle of the portion from the opening to the top of the L-shaped lug groove 323 is measured as the angle formed by the virtual straight line passing through the opening and the top of the L-shaped lug groove 323 and the tire circumferential direction.

The extending distance of the portion from the opening of the L-shaped lug groove 323 to the top is measured as the distance in the tire width direction from the opening of the L-shaped lug groove 323 to the top.

Further, in FIG. 8, the inclination angle of the portion from the top to the end of the L-shaped lug groove 323 with respect to the tire circumferential direction (dimension symbol omitted in the figure) is in the range of 20 [deg] or more and 50 [deg] or less. , Preferably in the range of 30 [deg] or more and 40 [deg] or less. Further, the angle formed by the inclination angle of the portion from the opening to the top of the L-shaped lug groove 323 and the portion from the top to the end is in the range of 40 [deg] or more and 140 [deg] or less, preferably 70. It is in the range of [deg] or more and 110 [deg] or less. Further, the extending distance from the opening to the end of the L-shaped lug groove 323 in the tire width direction (dimension symbol omitted in the figure) is 40 [%] or more with respect to the maximum contact width Wb2 of the outer center land portion 32. It is in the range of 80 [%] or less, preferably in the range of 50 [%] or more and 70 [%] or less.

The inclination angle of the portion from the top to the end of the L-shaped lug groove 323 is an angle formed by the virtual straight line passing through the top and the end of the L-shaped lug groove 323 and the tire circumferential direction, and is the above-mentioned L-shaped lug groove 323. The direction of inclination in the direction opposite to the inclination angle of the portion from the opening to the top (the direction in which the top of the L-shaped lug groove 323 opens) is measured as positive.

The extending distance of the portion from the top to the end of the L-shaped lug groove 323 is measured as the distance in the tire width direction from the opening of the L-shaped lug groove 323 to the top.

Further, in FIG. 8, the ratio of the extending distance from the opening to the top of the L-shaped lug groove 323 in the tire width direction and the extending distance from the opening to the end is in the range of 40% or more and 80% or less. Yes, preferably in the range of 40% or more and 67% or less (dimension symbols omitted in the figure). Further, the ratio of the extending length from the opening to the top of the L-shaped lug groove 323 in the tire circumferential direction to the extending length from the top to the end (dimension symbol omitted in the figure) is 20% or more and 60%. It is in the following range, preferably in the range of 25% or more and 50% or less (dimension symbols omitted in the figure).

For example, in the configuration of FIG. 8, the portion from the opening to the top of the L-shaped lug groove 323 has a linear shape or a gentle arc shape. On the other hand, the portion from the top to the end of the L-shaped lug groove 323 has a bent portion having a gentle bending angle between the top and the end of the L-shaped lug groove 323. Therefore, the groove center line of the L-shaped lug groove 323 has a first bending point at the top of the L-shaped lug groove 323 and a second bending point at the portion from the top to the end. As a result, the L-shaped lug groove 323 has a hook shape having two bent portions as a whole.

However, not limited to the above, since the portion of the L-shaped lug groove 323 from the top to the end has a linear shape or a gentle arc shape, the bending point of the portion from the top to the end may be omitted ( Not shown).

In the configuration of FIG. 2, the inner center land portion 33 includes a plurality of I-shaped lug grooves 333 in addition to the inner main lug groove 331 and the inner center block 332 described above.

As shown in FIG. 2, the I-shaped lug groove 333 has a linear, gently curved arc shape or a gently bent bent shape in a tread plan view. Further, the I-shaped lug groove 333 penetrates the inner center land portion 33 and opens to both edge portions of the inner center land portion 33. Further, the I-shaped lug groove 333 has a maximum groove width of 4.0 [mm] or more and a maximum groove depth of 4.5 [mm] or more. Further, a plurality of I-shaped lug grooves 333 are arranged in the tire circumferential direction with a predetermined pitch length. Also, each of the inner center blocks 332 comprises a single I-shaped lug groove 333. Therefore, the number of pitches of the I-shaped lug groove 333 is equal to the number of pitches of the inner main lug groove 331 and the inner center block 332.

Further, as shown in FIG. 8, the I-shaped lug groove 333 has an arc shape or a gently bent shape that is convex in one direction in the tire circumferential direction. Further, the convex direction of the I-shaped lug groove 333 in the tire circumferential direction is opposite to the convex direction of the L-shaped lug groove 323 of the outer center land portion 32. Further, the I-shaped lug groove 333 extends in the tire circumferential direction without going backward in one direction, and penetrates the inner center land portion 33 in the tire width direction.

Further, in FIG. 8, a virtual straight line (not shown) passing through the left and right openings of the I-shaped lug groove 333 is inclined in the same direction as the tire circumferential direction with respect to the inclination direction of the main lug groove 331. Further, the virtual straight line of the I-shaped lug groove 333 is inclined in the direction opposite to the tire circumferential direction with respect to the virtual straight line passing through the opening and the end portion of the L-shaped lug groove 323.

Further, as shown in FIG. 8, the I-shaped lug groove 333 is arranged so as to face the opening on the center peripheral groove 22 side of the L-shaped lug groove 323. Specifically, the I-shaped lug groove 333 extends in the tire width direction so as to extend the groove center line of the L-shaped lug groove 323. As a result, a sickle-shaped groove unit 3 including an L-shaped lug groove 323 and an I-shaped lug groove 333 is formed. Further, as shown in FIG. 2, the groove unit 3 (323, 333) is arranged so as to intersect the tire equatorial plane CL.

In the above configuration, since the inner center land portion 33 includes the I-shaped lug groove 333 extending the L-shaped lug groove 323 of the outer center land portion 32 described above, both of the adjacent center land portions are provided with the L-shaped lug groove. Compared with the configuration (not shown), the snow column shear force in the center region of the tread portion is increased, and the snow performance of the tire is improved.

Further, in FIG. 8, the inclination angle (dimension symbol omitted in the figure) of the I-shaped lug groove 333 with respect to the tire circumferential direction is in the range of 45 [deg] or more and 85 [deg] or less, preferably 55 [deg] or more. It is in the range of 75 [deg] or less. Further, the I-shaped lug groove 333 has a maximum groove width at the opening on the L-shaped lug groove 323 side and a minimum groove width at the other opening. Further, the groove width of the I-shaped lug groove 333 decreases monotonically from the opening on the L-shaped lug groove 323 side toward the other opening.

The inclination angle of the I-shaped lug groove 333 is measured as an angle formed by a virtual straight line passing through the left and right openings of the I-shaped lug groove 333 and the tire circumferential direction.

Further, in FIG. 8, as described above, the I-shaped lug groove 333 is arranged so as to face the opening of the L-shaped lug groove 323 to the center peripheral groove 22. Further, the I-shaped lug groove 333 extends in the tire width direction so as to extend the groove center line of the L-shaped lug groove 323.

Further, as shown in FIG. 8, the L-shaped lug groove 323 and the I-shaped lug groove 333 are opened with substantially the same opening width with respect to the center peripheral groove 22. Specifically, the opening width of the I-shaped lug groove 333 with respect to the center peripheral groove 22 is in the range of 0 [%] or more and 50 [%] or less with respect to the opening width of the L-shaped lug groove 323 with respect to the center peripheral groove 22. , Preferably in the range of 0 [%] or more and 15 [%] or less.

[Applicable target]
In this embodiment, as described above, a pneumatic tire has been described as an example of the tire. However, the present invention is not limited to this, and the configuration described in this embodiment can be arbitrarily applied to other tires within the scope of those skilled in the art. Examples of other tires include airless tires and solid tires.

[effect]
As described above, the tire 1 includes a peripheral groove 21 extending in the peripheral direction of the tire and a shoulder land portion 31 partitioned by the peripheral groove 21 (see FIGS. 2 and 3). Further, the shoulder land portion 31 is provided with a plurality of shoulder lug grooves 311 that intersect the tire ground contact end T and extend in the tire width direction and terminate in the ground contact surface of the shoulder land portion 31. Further, the shoulder lug groove 311 has a maximum circumferential width W1 of the shoulder lug groove 311 and is arranged at the center of the ground contact area of the shoulder land portion 31 and the main body portion 3111 extending from the main body portion 3111 to the tire ground contact end. It is provided with an extension portion 3112 that intersects T (see FIG. 4). Further, the circumferential width W2 of the shoulder lug groove 311 at the tire ground contact end T has a relationship of 0.20 ≦ W2 / W1 ≦ 0.90 with respect to the maximum peripheral width W1.

In such a configuration, (1) the wide main body portion 3111 is arranged in the central portion of the ground contact region of the shoulder land portion 31, so that the snow column shearing force is secured and the snow traction property of the tire is improved. Further, (2) since the narrow extension portion 3112 connects the main body portion 3111 and the tire contact end T, the tire is compared with the configuration in which the wide main body portion extends to the tire contact end (not shown). Pattern noise is reduced. Further, (3) the lower limit of the ratio W2 / W1 secures the effect of improving the snow traction property by the extending portion 3112, and the above lower limit ensures the effect of reducing the pattern noise by the extending portion 3112. These have the advantage of achieving both snow performance and noise performance of the tire.

Further, in this tire 1, the maximum circumferential width W1 of the shoulder lug groove 311 has a relationship of 0.10 ≦ W1 / P11 ≦ 0.50 with respect to the pitch length P11 of the shoulder lug groove (see FIG. 3). The lower limit ensures the effect of improving the snow traction property of the main body 3111, and the upper limit has the advantage of suppressing an increase in pattern noise due to the main body 3111 becoming excessive.

Further, in the tire 1, the circumferential width of the shoulder lug groove 311 monotonically increases from the tire ground contact end T toward the maximum circumferential width position of the shoulder lug groove 311 (see FIG. 4). This has the advantage that pattern noise is effectively reduced.

Further, in this tire 1, the entire extending portion 3112 has a groove width of 2.0 [mm] or more and a groove depth of 2.0 [mm] or more. This has the advantage that the extension portion 3112 opens when the tire touches the ground, and the effect of improving the snow traction property of the extension portion 3112 is ensured.

Further, in this tire 1, the distance D1 in the tire width direction from the tire contact end T to the maximum circumferential width position of the shoulder lug groove 311 is 0.50 ≦ D1 / with respect to the maximum contact width Wb1 of the shoulder land portion 31. It has a relationship of Wb1 ≦ 0.90 (see FIG. 4). As a result, the position of the main body portion 3111 having the maximum circumferential width W1 is optimized, and there is an advantage that the effect of improving the snow traction property by the main body portion 3111 is improved.

Further, in this tire 1, the distance D2 from the tire contact end T to the innermost point in the tire width direction of the shoulder lug groove 311 is 0.55 ≦ D2 / Wb1 ≦ with respect to the maximum contact width Wb1 of the shoulder land portion 31. It has a relationship of 0.95 (see FIG. 4). By the above lower limit, the extended length (distance D2) of the shoulder lug groove 311 is secured and the snow traction property of the tire is secured, and by the above upper limit, the shoulder from the innermost point P1 of the shoulder lug groove 311 to the shoulder of the shoulder land portion 31. There is an advantage that the distance to the edge portion on the peripheral groove 21 side is secured and the rigidity of the shoulder land portion 31 is secured.

Further, in the tire 1, the extension portion 3112 is defined as a groove portion having a continuous circumferential width of 1.00 times or more and 1.20 times or less with respect to the circumferential width W2 at the tire ground contact end T (FIG. FIG. 4). Further, the distance D3 from the tire contact end T to the inner end of the extension portion 3112 in the tire width direction has a relationship of 0.10 ≦ D3 / Wb1 ≦ 0.40 with respect to the maximum contact width Wb1 of the shoulder land portion 31. Has. By the above lower limit, the extension length (distance D3) of the extension portion 3112 is secured, the effect of reducing the pattern noise by the extension portion 3112 is secured, and by the above upper limit, the extension length of the main body portion 3111 is secured. Therefore, there is an advantage that the effect of improving the snow traction property by the main body portion 3111 is ensured.

Further, in the tire 1, the shoulder lug groove 311 has a linear shape or a gentle arc shape in a tread plan view, and extends from the tire ground contact end T to the maximum circumferential width position of the shoulder lug groove 311. It has an edge portion E1 and a second edge portion E2 having a linear shape or a gentle arc shape and being arranged facing the first edge portion E1 to partition the main body portion 3111 (see FIG. 4). Further, the inclination angle θb of the second edge portion E2 with respect to the tire circumferential direction at the maximum circumferential width position is 5 [deg] ≦ θa−θb ≦ 30 [deg] ≤ θa − θb ≦ 30 with respect to the inclination angle θa of the first edge portion E1 with respect to the tire circumferential direction. It has a relationship of deg]. In such a configuration, since the edge portions E1 and E2 of the shoulder lug groove 311 have different inclination angles θa and θb at the maximum circumferential width position, there is an advantage that the effect of improving the snow traction property by the main body portion 3111 is enhanced. ..

Further, in this tire 1, the inclination angle θa of the first edge portion E1 is in the range of 50 [deg] ≤ θa ≤ 90 [deg] (see FIG. 4). This has the advantage that the inclination angle θa of the first edge portion E1 is optimized.

Further, in this tire 1, the shoulder lug groove 311 has a V-shaped end portion, and the V-shaped bending angle φ is in the range of 30 [deg] ≦ φ ≦ 80 [deg]. This has the advantage that the V-shaped bending angle φ is optimized and the snow traction property of the tire is ensured.

Further, in this tire 1, the maximum groove depth H11 of the outer shoulder lug groove 311 in the tire ground contact region is 0.50 ≦ H11 / Hg1 ≦ 0.90 with respect to the maximum groove depth Hg1 of the outer shoulder peripheral groove 21. The groove wall angle α of the shoulder lug groove 311 at the maximum circumferential width position is in the range of 1 [deg] ≤ α ≤ 20 [deg] (see FIG. 6). This has the advantage of increasing the snow column shear force of the outer shoulder lug groove 311.

Further, the tire 1 is provided with an auxiliary groove 313 connected to the shoulder lug groove 311 in the tire non-grounded region and extending in the tire circumferential direction (see FIG. 3). This has the advantage of improving the design of the tire.

9 and 10 are charts showing the results of tire performance tests according to the embodiment of the present invention.

In this performance test, (1) snow performance and (2) noise performance were evaluated for a plurality of types of test tires. Further, a test tire having a tire size of 225 / 45R18 95W is assembled to a rim having a rim size of 18 × 7.5J, and an internal pressure of 240 [kPa] and a specified load specified by JATTA are applied to the test tire. Further, the test tires are mounted on all the wheels of the FR (Front engine Rear drive) vehicle having a displacement of 2.0 [L], which is the test vehicle.

(1) In the evaluation of snow performance, the test vehicle travels on a predetermined handling course on a snowy road at a speed of 40 [km / h], and the test driver performs a sensory evaluation of steering stability. This evaluation is performed by an index evaluation based on Comparative Example 1 (100), and the larger the value is, the more preferable. Further, if the numerical value is 98 or more, it can be said that the performance is properly secured.

(2) In the evaluation of noise performance, the passing noise (outside noise) of the vehicle is measured under the test conditions compliant with R117-2 (Regulation No. 117 Revision 2) of ECE (Economic Commission for Europe). Then, based on this measurement result, an index evaluation is performed with Comparative Example 1 as a reference (100). The larger the value, the more preferable this evaluation.

The test tires of the examples have the configurations of FIGS. 1 and 2. Specifically, the test tire includes three peripheral grooves 21 to 23 and four rows of land portions 31 to 34, and the left and right shoulder land portions 31, 34 have a plurality of shoulder lug grooves 311, 341 and a plurality of shoulder lug grooves 31 and 34. It includes sipes 312 and 342, respectively. Further, the outer shoulder peripheral groove 21 has a maximum groove width of 4.0 mm] and a maximum groove depth of 6.5 [mm], and the center peripheral groove 22 has a maximum groove width of 10.7 [mm] and 7. It has a maximum groove depth of 6 [mm], and the inner shoulder peripheral groove 23 has a maximum groove width of 10.9 [mm] and a maximum groove depth of 7.6 [mm]. Further, the maximum contact width Wb1 of the shoulder lug grooves 311 and 341 is 32 [mm].

In the test tire of the comparative example, in the test tire of the first embodiment, the outer shoulder lug groove 311 has a constant circumferential width (not shown).

As the test results show, it can be seen that the test tires of the examples have both snow performance and noise performance of the tire.

1 tire; 3 groove unit; 11 bead core; 12 bead filler; 13 carcass layer; 14 belt layer; 141, 142 cross belt; 143 belt cover; 15 tread rubber; 16 sidewall rubber; 17 rim cushion rubber; 21, 23 shoulders Circumferential groove; 22 Center peripheral groove; 31, 34 Shoulder land area; 32, 33 Center land area; 311 311A to 311D Outer shoulder lug groove; 3111 Main body part; 3112 Extension part; 312 Sipe; 313, 313A, 313B Auxiliary Groove; 321 Outer main lug groove; 322 Outer center block; 323 L-shaped lug groove; 331 Inner main lug groove; 332 Inner center block; 333 I-shaped lug groove; 341 Inner shoulder lug groove; 342 Sipe

Claims (12)

A tire having a peripheral groove extending in the circumferential direction of the tire and a shoulder land portion defined by the peripheral groove.
The shoulder land portion is provided with a plurality of shoulder lug grooves that intersect the tire ground contact end and extend in the tire width direction and terminate within the ground contact surface of the shoulder land portion.
The shoulder lug groove has a maximum circumferential width W1 of the shoulder lug groove and intersects a tire ground contact end extending from the main body portion with a main body portion arranged in the central portion of the ground contact region of the shoulder land portion. Equipped with an extension
A tire characterized in that the circumferential width W2 of the shoulder lug groove at the tire ground contact end has a relationship of 0.20 ≦ W2 / W1 ≦ 0.90 with respect to the maximum peripheral width W1. The tire according to claim 1, wherein the maximum circumferential width W1 of the shoulder lug groove has a relationship of 0.10 ≦ W1 / P11 ≦ 0.50 with respect to the pitch length P11 of the shoulder lug groove. The tire according to claim 1 or 2, wherein the circumferential width of the shoulder lug groove monotonically increases from the ground contact end of the tire toward the maximum circumferential width position of the shoulder lug groove. The tire according to any one of claims 1 to 3, wherein the entire extending portion has a groove width of 2.0 [mm] or more and a groove depth of 2.0 [mm] or more. The distance D1 in the tire width direction from the tire contact end to the maximum circumferential width position of the shoulder lug groove has a relationship of 0.50 ≦ D1 / Wb1 ≦ 0.90 with respect to the maximum contact width Wb1 of the shoulder land portion. The tire according to any one of claims 1 to 4. A claim that the distance D2 from the tire ground contact end to the innermost point in the tire width direction of the shoulder lug groove has a relationship of 0.55 ≦ D2 / Wb1 ≦ 0.95_ with respect to the maximum ground contact width Wb1 of the shoulder land portion. The tire according to any one of Items 1 to 5. The extension portion is defined as a groove portion having a continuous circumferential width of 1.00 times or more and 1.20 times or less with respect to the circumferential width W2 at the tire contact end, and is defined as a groove portion.
Claim that the distance D3 from the tire ground contact end to the inner end of the extension portion in the tire width direction has a relationship of 0.10 ≦ D3 / Wb1 ≦ 0.40 with respect to the maximum ground contact width Wb1 of the shoulder land portion. The tire according to any one of Items 1 to 6. The shoulder lug groove has a linear shape or a gentle arc shape in a tread plan view, and has a linear shape or a gentle arc shape with a first edge portion extending from the tire ground contact end to the maximum circumferential width position of the shoulder lug groove. It has a circular arc shape and has a second edge portion which is arranged so as to face the first edge portion and divides the main body portion, and also has a second edge portion.
The inclination angle θb of the second edge portion with respect to the tire circumferential direction at the maximum circumferential width position is 5 [deg] ≤ θa − θb ≦ 30 [deg] with respect to the inclination angle θa of the first edge portion with respect to the tire circumferential direction. ] The tire according to any one of claims 1 to 7. The tire according to claim 8, wherein the inclination angle θa of the first edge portion is in the range of 50 [deg] ≤ θa ≤ 90 [deg]. One of claims 1 to 9, wherein the shoulder lug groove has a V-shaped end portion and the V-shaped bending angle φ is in the range of 30 [deg] ≤ φ ≤ 80 [deg]. Tires listed in. The maximum groove depth H11 of the shoulder lug groove in the tire ground contact region has a relationship of 0.50 ≦ H11 / Hg1 ≦ 0.90 with respect to the maximum groove depth Hg1 of the shoulder peripheral groove, and the maximum circumference. The tire according to any one of claims 1 to 10, wherein the groove wall angle α of the shoulder lug groove at the direction width position is in the range of 1 [deg] ≤ α ≤ 20 [deg]. The tire according to any one of claims 1 to 10, further comprising an auxiliary groove extending in the tire circumferential direction connected to the shoulder lug groove in the tire non-grounded region.

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